[Warning: This story contains spoilers from Thursday's 200th episode of Grey's Anatomy, "Puttin' on the Ritz."]
Prepare to really get to know Alex Karev on ABC's Grey's Anatomy.
After 10 seasons, the medical drama has introduced Alex's (Justin Chambers) estranged father -- currently known as "Junkie Jake" (Dexter's James Remar), who arrived at Grey Sloan Memorial after a heroin-induced car crash.
In the closing moments of the 200th episode, Jo (Camilla Luddington) revealed the results of Alex's blood test, which conclusively proved that Cristina and Shane's patient was his father.
"We're going to learn a lot about Alex's past and about where he is now," showrunner Shonda Rhimes tells THR of the upcoming arc. "He's been a character who has really struggled with his own morality and being a good guy or not being a good guy. He's gotten really successful at that and it's going to be interesting whether he backslides in the face of having his dad here or not."
After he arrived at the hospital, Alex instantly believed "Junkie Jake" -- with his familiar voice and "Sinatra" crack -- was his estranged father, whom he hasn't seen in 20 years. But it was Jo confirming it -- and jumping the gun in doing so -- that sent Karev into familiar territory: storming off and avoiding the discussion.
"[Their relationship] is very distant and volatile; t hey don't really know each other and Alex only knows him as the guy that left him," Remar tells THR. "Due to the character's problems, he hasn't really been able to be responsible to anybody that he loves. the guy is a drug addict."
"Jo is a person who finds family incredibly important because she didn't have one and it's hard for her to understand why somebody wouldn't want to know their family no matter what," Rhimes says of how "Junkie Jake" will impact the new couple.
Chambers, for his part, notes that having Jo to lean on as he navigates the emotional baggage that comes with his father's arrival will help bring the duo closer together.
"It's going to deepen their relationship because she's going to be there for him to help him get through it," Chambers tells THR. "She comes from the same kind of background that Alex does and can call him on it: 'Grow up, get over it, move on. He's still your dad,' and those kind of things. They're not easy and you're going to see Alex struggle with that."
Chambers notes that the details of Alex's childhood that will come up during the story line will highlight just how much he's had to overcome, which will make his accomplishments that much more impressive.
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"I'm surprised Alex got through all that and became a doctor," Chambers says. "That's fairly impressive and that's inspiring for people because you can come from a messed up background and still overcome that and become better for it. Alex turned around and became a better man from it. He still has a lot to learn."
Luddington, meanwhile, says Jo wants to be the typical "supportive girlfriend" but may take it too far, "inserting herself even when it's not necessarily wanted."
"It's a little testy because Jo really wants Alex to always be happy and have a family that she never had," she explains. "She's hoping that they will reconcile but it's a tricky situation for them. There are times where they definitely butt heads over it; it's a very sensitive subject for him and that relationship is full of a lot of hurt between him and his dad."
Are you looking forward to Alex's upcoming storyline? Hit the comments below with your thoughts. Grey's Anatomy airs Thursdays at 9 p.m. on ABC.